Exercise-Induced Intrapulmonary Arteriovenous Shunt in a Patient Complaining of Dyspnea during Strenuous Exercise.

A 51-year-old highly fit man presented for dyspnea with strenuous aerobic exercise. The patient was asymptomatic and all tests were normal at rest. With increasing exercise intensity, he suddenly complained of dyspnea and showed a severe exercise-induced hypoxemia with an excessive alveolar-arterial oxygen tension difference. In agitated saline contrast echocardiography at peak exercise, a large amount of left to right shunt was identified after > 5 cardiac cycles, which suggests the presence of exercise-induced intrapulmonary arteriovenous shunt in this patient.